Hardware and the Software

A computer system has two parts-hardware and the software. The hardware is useless until we do not have the requisite software. The software is necessary to run the computer. There are different types of software available.

Hardware:
Computer data processing involves equipment that can perform the following functions: data preparation; input to the computer; computation; control and primary storage; secondary storage and output from the computer. Equipment, which are
connected directly to the computer, are termed as on-line whereas the equipment, which are used separately and are not connected, are called off-line.

Software :
Software is a set of instructions that directs the computer to process information. These instructions are called programs. Without software, the computer cannot work, A commonly used analogy is that the computer hardware is the engine, while the software is the fuel that allows the engine to operate. Without relent software, the hardware would be useless. There are two types of software available for computers-system software and application software.

System Software: system software program coordinates the operations of the various hardware components of the computer. The system software or operating system program helps the user to actually operate the computer system. This is an interface between the user and the computer.

The operating system oversees the processing of the application programs all inputs to and outputs from the system. The computer manufacturers usually provide system software. The various types of computers require different types of system software program in order to operate. Some of the most popular are DOS, Windows 2000/XP and LINUX. The system software contains those programs that control and support the computer system and its data processing applications. It includes:
A. The Operating System; and
B. The Language Translators.

Operating System (OS): Considerable time is normally wasted in computer setups supervised by the operator. During compilation or assembly, run-time required to input the magnetic tape (consisting of the main program and subroutines etc ) is substantial and would naturally, be pinching. Likewise several application programs (viz, inventory control, Accounts receivables etc.) Would be read into the CPU in turn every day or so.
Operating system is an organized collection of integrated set of specialized programs that controls the overall operations of a computer. It helps the computer to supervise and manage its resources.

Language Translator :
(a) Assembler: An assembler is used to convert the program written in assembly language into machine language.
(b) Compiler: Compiler translates a source program that is usually written in aghigh level language by a programmer into machine language. The compiler is compiler is capable of replacing single source program statement with a series of machine-language instructions or with a subroutine. For each high level language the machine requires a separate compiler.
(c) Interpreter: Interpreter translates each source program statement into a sequence of machine instructions and then executes these machine instructions before translating the next source language statement. Interpreters are also unique for each high level language. Basically, the function of the compiler and interpreter are the same; the only difference is that compiler provides a separate object program but the interpreter does not.

Application Software:
Application software is a set of program designed for specific sues or applications such as word processing, graphics or spreadsheet analysis. Application software can be custom-made but is usually purchased off the shelf.
Normally to use an application program like FoxPro, we load the program into computer’s memory, execute (run) the program; and then create, edit or update a file or databas4 file. When we have finished, we need to save the work we have done on a disk. If we do not save our work and we turn off the computer, it is erased from memory and everything we have done may be lost.

Programming Languages :
A language is a system of communication. In order to communicate with each other, humans need languages like English, Hindi etc. In the same manner, for communicating with the computer, we use computer language called programming language. A programming language consists of all the symbols. Characters and usage rules that permit people to communicate with computers. Learning to program requires learning all these symbols and rules. A program is a set of l9ogically related instructions that are arranged in a sequence that guides the computer to solve a problem. The process of writing a program is called Programming.

Machine Language :
This is a sequence of instructions written in the form of binary numbers consisting of is and Os to which the computer responds directly. A machine language would have tow parts. The firs part is the command or an operation that tells the computer what functions are to be performed. The second part of the instruction is the operand that tells the computer where to find or store the data on which the desired operation is to be performed.

Assembly Language :
To ease the burden of the programmer, mnemonic operation codes and symbolic addresses were developed during the early 1950s. The Mnemonic refers to a memory aid. One of the first steps for improving the program preparation process was to substitute letter, symbols and mnemonics for the mnemonic machine-language operation codes. Today every computer has a mnemonic code, though the actual symbols vary among makes and models, Machine language is still used by the computer as it processes data but assembly language software first translates the specified operation code symbol into its machine language equivalent.
A program written by a programmer in an assembly language is called a Source program, After this source program has been converted into machine code by an assembler; it is referred to as an Object Program.

What is a Computer?

A Computer is an electronic machine with some mechanical facilities and is used mainly for data processing. It performs arithmetical and logical operations on the input data and gives the desired output. But in between the input and output, there is a step called processing which is done by the computer and processing methods on setups are provided by the users by a logical instruction known as program.



Functional Units of a computer
A computer is also a system because it is a group of integrated parts which are used to solve any problem by executing a suitable program.
Basically, there three types of functional unit of computer.
(1) Input/Output unit
(2) CPU
(3) Memory

Input/Output unit
A computer uses input devices for data entry purposes. Some input devices allow direct communication between the user and the computer. Devices connected directly to a computer are said to be on-line devices; mouse, light pen, touch screen etc. are all on-line devices.
Similar to input devices, output devices have an inter face between the user and the computer. These devices take machine coded output results from the processor and convert them into a form that can be used by human beings.

CPU(Central Processing Unit)
Central processing unit is the heart of any computer system. It consists of primary memory unit, arithmetic and logic unit and control unit.

Control Unit (CU):-Central unit controls all the hardware operations, i.e., those of output units, storage and of the processor itself. It fetches the requisite from main storage, stores it in a number of special registers, interprets the registers, interprets the instructions and follows the instructions to be executed by giving signals (or commands) to the appropriate hardware devices.

Arithmetic and Logic Unit (ALU):- The arithmetic and units in computers are capable of performing addition, subtraction, division a Subtraction, division and multiplication as well as some logical operations. The ALU has a number of selection lines to select a particular micro-operation in the unit.
Memory:-The memory or storage section of the computer consists of the devices used to store the in formation that would be used during the computations. The memory section of the computer is also used to hold both intermediate and final results as the computer proceeds through the program.
Memory can be divided into two categories-Primary Memory and Secondary Memory. Details of Primary Memory or Main Memory are as follows.
(A) RAM (Random Access Memory); and
(B) ROM (Read Only Memory).

Characteristics of a Computer
A computer is a fast and accurate electronic system that is designed to accept and store input data, process them and produce output results using the instructions of a stored program.
Speed and Accuracy :-Computer executes one instruction at a time. It can add and subtract numbers, compare characters to determine string matching and copy numbers and characters. There is nothing new in these operations.
In additions to their high speeds, computers have high accuracies as well. The circuits in a computer have electronic parts which do not have wear and tear.
Processing Capabilities:- Computer processing involves manipulating the symbols that represent things required by the user. People have been using characters, numbers and other symbols and computer processing simplifies this human task by providing the necessary speed and accuracy.
Data and Information:-Data are represented by symbols. After processing the data, information is produced. Thus information is data arranged in an order that would be useful to the user.
Data processing consists of three basic activities.
(1) Capturing the input data
(2) Manipulating the data and
(3) Handling the output results.

Capturing the input data: Data must be recorded or captured on some medium before they could be processed.
Manipulating the data: The following operations may be performed on the data.

(A) Classifying:
(B) Calculating:
(C) Storing:
(D) Summarising:

Handling the output results: Once data have been captured and manipulated, one or more of the following operations may be needed.

(A)Storing and Retrieving:
(B)Communicating and Reproducing:

Computer Processing Operations: A computer can perform only the following four basic operations through it can carry out the data processing activities.
(1) Input\Output operations
(2) Text manipulation and calculation operations
(3) Logic\Comparison operations
(4) Storage and Retrieval operations

Memory Capability

Computer systems have the ability of total and instant recall of data and an almost unlimited capacity to store these data. A typical mainframe computer system would have billions of characters and perhaps, thousands of graphic images, stored and available for instant recall.